1. Field of the Invention
This invention relates to a process for the manufacture of surface-active sulfophosphoric-acid-(partial)-alkyl-esters and their alkali-, alkaline earth-, ammonium- and/or amine salts by the sulfonation of phosphoric acid esters and the subsequent hydrolysis of the sultone intermediate stages.
2. Description of the Related Art
Although the use of phosphates and phosphonates as builders in detergent recipes is well known, the use of phosphoric compounds as surfactant is much less common.
The synthesis of surfactants containing phosphorus through the reaction of saturated alpha-bromo-fatty acid esters with triethylphosphite is disclosed by Maurer et. al. in J. Am. Oil Chem. Soc. 41, 205 (1964). Such alpha-phosphono-fatty acid esters have only average surface-active properties. The manufacture of alkyl phosphinates by the reaction of alpha-olefins with phosphorous or hypophosphorous acids is also known as disclosed by C. Herranz in J. Am. Oil Chem. Soc. 64, 1038 (1987). These substances also have only moderate washing and foaming properties.
Phosphoric acid esters with P-O-C-bonds have clearly improved surfactant properties as compared with the surfactants described by Maurer and Herranz, in which phosphorus is directly linked with a carbon chain. It is known, for example, that alkyl phosphates can be used as wetting agents, antistatic agents, emulsifying agents and as detergents and cleaning agents as disclosed by A. J. Olenick, W. C. Smith in Soap, Cosm. Chem. Spec. 7, 26 (1986). However, these substances have only a slight foaming capacity and they are less resistant to hard water. Some are poorly soluble in water.
The use of alkyl phosphates as antistatic agents for synthetic fibers is also known, as disclosed in Acta Polym. 38, 5 (1987). These materials are manufactured by the reaction of alcohols or alcohol-polyoxy-alkyl-ethers with POCl.sub.3.